| 摘要 |
<p>PURPOSE:To contrive improvement of work efficiency by holding a pressure in a circuit to a low value in a region of low engine speed and to a high value in a region of high engine speed. CONSTITUTION:A pressure in a circuit of a cargo handling hydraulic cylinder 7 is held to a low value in a region of low rotational speed of an engine 1 such as at idling time and to a high value in a region of high rotational speed of the engine 1. Accordingly, at the time of low rotational speed of the engine 1, an engine-stall can be prevented by decreasing a load acting on the engine 1. At the time of high speed rotation of the engine 1, high load work can be performed in the hydraulic cylinder 7. In this way, troublesomeness by the engine-stall can be eliminated to improve work efficiency.</p> |
